Wound healing compositions including cyanoacrylate monomers and phenytoin

ABSTRACT

A monomeric adhesive composition includes a stabilized polymerizable monomer, such as a 1,1-disubstituted monomer, including a cyanoacrylate, and a wound healing agent, wherein the wound healing agent is 5,5-disubstitutedhydantoin, including phenytoin; and a method for making said composition.

FIELD OF THE INVENTION

The present invention is directed to a stable, sterilizable liquidadhesive composition containing a wound healing accelerator, a5,5-disubstitutedhydantoin, including phenytoin, and the method formaking such compositions for industrial and medical uses.

BACKGROUND OF THE INVENTION

Wound management has been one of the most challenging tasks for medicalprofessionals.

In the past, many wound healing agents and methods for local woundmanagement have been developed. Some of the traditional wound healingagents, though now less widely used, are still beneficial in certainclinical settings for wound treatment. Such wound healing methodsinclude liquid or semi-solid formulations of povidone-iodine, silver,and polyhexamethlene biguanide used topically or incorporated intodressings to promote wound healing. Additional traditional approaches towound healing include physiological saline solution, silver nitrateointment, and dressings including gauze, cotton, wool, and synthetic ornatural bandage.

Most of the traditional wound healing methods have been replaced bymodern wound management techniques and increasingly more studies havebeen dedicated to develop methods and agents to promote wound healing.

Topical application of biologically active compounds has been proven tobe an effective method for promoting wound healing. These activecompounds include growth factors, mitogens, and hormones. However, suchapplications are limited in that it is difficult to regulate the dosageof the active compounds and the compounds rapidly degrade. For example,U.S. Patent Application Publication No. 20060188486 to Carpenter et al.discloses wound healing polymer compositions that release a woundhealing agent at a controlled rate. The wound healing agents disclosedinclude proteinaceous growth factors, vascular endothelial growthfactors, anti-proliferant agent, antimicrobials, anti-inflammatoryagents, tissue grafts and wound healing cells.

One of the most popular techniques among modern methods for promotingwound healing is the application of monomer and polymer tissueadhesives. Included among these adhesives are the 1,1-disubstitutedethylene monomers and polymers, such as the alpha-cyanoacrylates. Sincethe discovery of the adhesive properties of such monomers and polymers,they have found wide use due to the speed with which they cure, thestrength of the resulting bond formed, and their relative ease of use.These characteristics have made alpha-cyanoacrylate adhesives theprimary choice for numerous applications even outside the medical arena,including industrial and home use in bonding plastics, rubbers, glass,metals, and wood.

Tissue adhesives have been investigated extensively as the healing agentfor topical wounds. Compared to suture and other wound closure agents,cyanoacrylate adhesives demonstrate similar cosmetic results, but moreimportantly, improve the rate of wound closure (Quinn et al. JAMA, 277,1527-30, 1997). It has also been found that cyanoacrylate tissueadhesives can be the preferred method in terms of cosmetic appearancefor the cutaneous closure of facial lacerations (Simon et al. J. Emerg.Med. 16, 185, 1998). Besides faster wound closure and better cosmesis,advantages of cyanoacrylate adhesives over suture or staples alsoinclude lower infection rates. And, the recently FDA approved andcommercially available SurgiSeal® topical skin adhesive, which is a2-octylcyanoacrylate, has shown a desirable water vapor transmissionrate (WVTR) which could be beneficial to wound healing. (SurgiSeal®topical skin adhesive is manufactured by Adhezion Biomedical, LLC,Wyomissing, Pa.)

Although the source for this characteristic is not understood it hasbeen observed that cyanoacrylate compositions inherently possess someantimicrobial activity. In particular, cyanoacrylate compositionsthemselves are believed to prevent the growth of some types ofmicroorganisms within the compositions. But because this property islimited, in order to further enhance wound healing using cyanoacrylateadhesives, different wound healing agents have been incorporated intocyanoacrylate tissue adhesives. For example, U.S. Patent ApplicationPublication No. 20050042266 to Narang and U.S. Pat. Nos. 5,684042,5,762,919, 5,811,091 and 5,783,177 to Greff et al. disclose that aneffective amount of antimicrobial agents can be incorporated intocyanoacrylate adhesive compositions to promote wound healing.

U.S. Pat. No. 6,214,332 to Askill et al. discloses antimicrobialcyanoacrylate ester compositions which may further include medicaments,such as growth factors such as epidermal growth factor, platelet derivedgrowth factor, transforming growth factors, keratinocyte growth factorand fibroblast growth factor. However, as a general matter, it has beena challenging task to incorporate medicaments into cyanoacrylateadhesives. Most medicaments are not soluble in cyanoacrylates.Additionally, many if not most medicaments negatively affect thepolymerization rate of the monomer composition, either by acting asinhibitors or as initiators. Thus, the cyanoacrylate could be preventedfrom curing (polymerizing) or induced to prematurely polymerizeresulting in an undesirable reduction or destruction of the shelf-lifestability of the cyanoacrylate. Additionally, incorporation ofmedicaments could also affect the viscosity of the composition and theresulting performance of the cyanoacrylate in terms of cure time andbonding strength. In addition, medicaments based on protein could beinactivated due to the binding of protein to cyanoacrylate, as U.S. Pat.No. 5,684,042 to Greff et al. discloses. Therefore, better methods andcompositions are still needed with regard to promoting wound healing.

Another wound healing accelerator is phenytoin. Phenytoin refers todiphenylhydantoin or 5,5-diphenylimidazolidine-2,4-dione, whichoriginally was introduced into therapy in 1937 as an effectiveanticonvulsant in the treatment of epileptic patients. It has been notedthat a common side effect of phenytoin treatment for seizures is thedevelopment of fibrous overgrowth of gingival (gums). It is believedthat this occurs by the phenytoin stimulating responsive sub-populationof fibroblasts to synthesize the increased amount of collagen. The greatpotential of phenytoin in wound healing is thus derived from the obviousstimulatory effect of phenytoin on connective tissue.

U.S. Patent Application Publication No. 20090022779 to Kelly et al.discloses gel-based phenytoin formulations suitable for topicalapplication to wound sites. The disclosed compositions contain phenytoindissolved in an aqueous component of gel and solid powder which entrapsthe phenytoin. The gelling agent can be selected from alginic acid,chitosan and its derivatives, and a carbomer.

In vivo and clinical studies have demonstrated that topical phenytoinprovides advantages as a wound healing agent. A controlled clinicaltrial, using phenytoin by applying it to periodontal patients withsurgical wounds, reported that phenytoin accelerated wound healing andreduced inflammation and pain (Shapiro, Exp. Med. Surg. 16, 41-53,1958). Furthermore, a large number of clinical studies concluded thatphenytoin therapy has a beneficial effect on healing of various woundtypes including surgical wounds, burns, pressure ulcers, traumaticwounds, decubitus ulcers, venous stasis ulcers, and diabetic ulcers,many of which are difficult and chronic wounds (Naeini et al. J. Anim.Vet. Adv. 12, 1537-1545, 2008; Talas et al. Biochem. Pharmacol. 57,1085-1094, 1999; Bhatia et al., Dermatol. Online J. 10, 5, 2004;Scheinfeld Dermatol. Online J. 9, 6, 2003). It is believed thatphenytoin has a stimulatory effect on tissue growth by improvinggranulation tissue formation which is beneficial to wound healing.

Besides enhancing wound healing, phenytoin has an antimicrobial propertyand has been shown to decrease the bacterial load of wounds as proved bya number of clinical studies (Pendse et al. Int. J. Dermatol. 32, 214-7,1993). In addition, topical phenytoin therapy can relieve local painwhen applied onto the wound site due to its membrane-stabilizingproperty thereby providing rapid relief for patient's comfort.Additionally, phenytoin can reduce inflammation and wound transudation.And, as a wound healing agent, phenytoin could possibly accelerate nerveregeneration. Other advantages are that phenytoin is safe to use, costeffective and readily available as opposed to expensive alternativessuch as a mixture of synthetic growth factors.

Considering the established efficacy of phenytoin in promoting woundhealing, there is a clear need for methods through which the effectivewound healing property of phenytoin may be provided in a convenient,stable, efficacious and reproducible manner to local wounds.

A need also exists for improved adhesive compositions, especially formedical uses, that contain medicaments, but where the performance of theadhesive composition is not compromised.

SUMMARY OF THE INVENTION

The present invention provides sterilizable, stable, polymerizablecyanoacrylate compositions containing a 5,5-disubstitutedhydantoin woundhealing accelerator, including phenytoin, for use in the medical field.

The instant inventors have discovered a novel composition incorporatinga 5,5-disubstitutedhydantoin wound healing accelerator intocyanoacrylate adhesives enabling the accelerator to be delivered andreleased to a wound site during the process of wound closure and/orhealing. This unique combination of the desirable characteristics ofboth cyanoacrylate adhesive film and 5,5-disubstitutedhydantoins to healwounds will provide enhanced wound healing effects not experiencedheretofore and a superior technique for wound management.

The instant invention realizes the combined benefits of bothcyanoacrylate adhesives and 5,5-disubstitutedhydantoins. The naturallyantibacterial characteristic of cyanoacrylate in addition to its woundsealing and physical film barrier properties is enhanced by the tissuegrowth stimulating, antimicrobial, anesthetic, and anti-inflammatoryproperties of one compound, a 5,5-disubstitutedhydantoin, especiallyphenytoin.

After topically applying to wounds or incisions, the inventivecyanoacrylate adhesives cure to form polymer films that provide acontrolled and slow release of the accelerator medicament.

Production of the sterilized composition includes placing a homogeneoussolution of stabilized polymerizable monomer and the wound healing agentin a container, sealing the container and sterilizing the container andthe mixture. The compositions produced, packaged and sterilizedaccording to the present invention are stable, and have extendedutility, as compared to adhesive compositions of the prior art.

The present invention also provides a method for homogenouslyincorporating the healing accelerator into liquid cyanoacrylate monomeradhesive compositions without inducing the premature polymerization ofsuch adhesives. The combination of heating the heterogeneous mixture ofhealing accelerator and cyanoacrylate compositions to an elevatedtemperature and stabilizing the cyanoacrylate monomer with desirablestabilizers prior to incorporation of the accelerator(“pre-stabilizing”), results in a stable and homogeneous solution ofcyanoacrylate containing 5,5-disubstitutedhydantoin. The resultingcyanoacrylate compositions containing the healing accelerator can alsobe sterilized and exhibit an extended shelf life.

The present invention also provides a kit for applying the sterilizedcyanoacrylate adhesive compositions, including an applicator andcyanoacrylate formulations containing a 5,5-disubstitutedhydantoin asthe wound healing accelerator.

Also provided is a method of applying the sterilized liquid inventivewound healing cyanoacrylate compositions to tissue, and the resultingfilm.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention relates to formulations and methods for treating wounds.The present invention provides a formulation of cyanoacrylate monomerscontaining a wound healing accelerator, 5,5-disubstitutedhydantoin,including phenytoin. Also provided is a method for incorporating thehealing accelerator into cyanoacrylate monomers by heating theheterogeneous mixture of accelerator and cyanoacrylate monomers to amildly elevated temperature. The formulations containing bothcyanoacrylate monomers and healing accelerator are pre-stabilized withsuitable amounts of the desirable polymerization inhibitors. The saidformulations are sterilized with suitable sterilization methods so thatcyanoacrylate formulations containing the 5,5-disubstitutedhydantoin canbe used in the medical field for the treatment of wounds, includingwound closure and for the improvement of wound healing. According to thepreferred embodiments of the present invention, the sterilizedcyanoacrylate formulations containing 5,5-disubstitutedhydantoin canprovide a long term stable shelf life of at least 2 years.

It is believed that the compositions of the present invention aresuitable for use in a variety of medical settings but should beparticularly applicable in a surgical setting to promote the healingprocess of surgical incisions. In addition, it is contemplated that suchcompositions based on both cyanoacrylate and 5,5-disubstitutedhydantoincan be most beneficial in the treatment of chronic wounds or those whichare resistant to healing. According to the present invention, it isexpected that this composition having the wound healing activity of theaccelerator in combination with the effects of the wound sealingability, and other known benefits, of cyanoacrylates will provide foroverall improved wound healing. After topically applying to the woundsor surgical incisions, the liquid cyanoacrylate adhesives are cured toform polymer films with tissue growth stimulating, antimicrobial andmechanical barrier properties. By incorporating5,5-disubstitutedhydantoin within a cyanoacrylate polymer, a controlledand slow release of the accelerator medicament can be achieved.

The wound healing agent or accelerator is a 5,5-disubstitutedhydantoinas set forth in Formula I below, wherein R is any alkyl or aromaticgroup, preferably an unsubstituted or substituted phenyl group. Each Rsubstituent may be the same or different.

The preferred accelerator is 5,5-diphenylhydantoin also known asphenytoin, 5,5-diphenyl-2,4-imidazolidinedione,5,5-diphenyl-imidazolidine-2,4-dione, phanantin, dintoin, and dillantin.The structure of phenytoin is shown in Formula II.

A desirable feature of phenytoin for use in medical applications to aidin or accelerate wound healing is that it can be multi-functional orsimultaneously provide more than one benefit. As discussed earlier, itsfunctions include acting to stimulate tissue growth, as an analgesic torelieve local pain, as an agent to reduce transudation or exudation fromwounds, and as an anti-inflammatory to reduce inflammation. Additionallyit acts as an antimicrobial agent to reduce the bacteria load of woundsand/or tissue. By antimicrobial is meant it destroys microbes includingbacteria, fungi, viruses and microbial spores preventing theirdevelopment and pathogenic action.

According to the present invention, an effective amount of wound healingpromoter, is incorporated into the pre-stabilized liquid monomericcyanoacrylate adhesive compositions to form a homogeneous liquidadhesive product. The solid 5,5-disubstitutedhydantoin is added to theliquid cyanoacrylate monomers and this heterogeneous mixture is stirredat a mildly elevated temperature over a certain period to form ahomogeneous mixture, as they are not soluble in cyanoacrylate monomersat room temperature.

Suitable temperatures range from about 40° C. to about 100° C.,preferably from about 50° C. to about 90° C., more preferably from about60° C. to about 90° C., and even more preferably from about 70° C. toabout 80° C. After continuous stirring at this elevated temperature, themixture of cyanaocrylate monomers and wound healing accelerator becomesa homogeneous solution within about 1 to 2 hours. Standard mixingequipment and techniques are suitable. The 5,5-disubstitutedhydantoins,including phenytoin are readily available from major chemicaldistributors.

According to embodiments of the present invention, the amount of5,5-disubstitutedhydantoin incorporated into the cyanoacrylatecomposition will vary depending on the type of cyanoacrylate. Withoutbeing bound by a particular theory, it is believed that the shorter thecyanoacrylate side groups, the more wound healing accelerator can bedissolved into solution with the cyanoacrylate. When mixing with a2-octylcynaoacrylate, generally, phenytoin is present in an amount offrom about 0.05% to about 0.5%, preferably from about 0.05% to about0.3% and more preferably from about 0.1% to 0.2%. (based on the totalweight of all components in the solution). When mixed with n-butylcyanoacrylate monomer, the phenytoin is present in an amount of fromabout 0.1% to about 1%, preferably from about 0.2% to about 0.8%, andmore preferably from about 0.3 to about 0.5%. One skilled in the monomerand polymer field will be able, with some routine experimentation, todetermine the amount of 5,5-disubstitutedhydantoin that can be added tothe specific cyanoacrylate used.

One or more monomer may be included in the adhesive composition.Monomers that may be used in this invention are readily polymerizable,e.g., anionically polymerizable or free radical polymerizable, to formpolymers. Preferred monomers include 1,1-disubstituted ethylene monomersof the formula III:

HRC═CXY   (III)

wherein X and Y are each strong electron withdrawing groups, and R is H,—CH═CH₂, or provided that X or Y is a cyano group, R is a C₁-C₄ alkylgroup.

Examples of monomers within the scope of formula (I) includealpha-cyanoacrylates, vinylidene cyanides, C₁-C₄ alkyl homologues ofvinylidene cyanides, dialkyl methylene malonates, acylacrylonitriles,vinyl sulfinates and vinyl sulfonates of the formula CH₂═CX′Y wherein X′is —SO₂R′ or —SO₃R′ and Y′ is —CN, —COOR′, —COCH₃, —SO₂R′ or —SO₃R′, andR′ is H or hydrocarbyl.

Preferred monomers of formula (III) for use in this invention arealpha-cyanoacrylates. These monomers are known in the art and have theformula (IV):

wherein R² is hydrogen and R³ is a hydrocarbyl or substitutedhydrocarbyl group; a group having the formula —R⁴—O—R⁵—O—R⁶, wherein R⁴is a 1,2-alkylene group having 2-4 carbon atoms, R⁵ is an alkylene grouphaving 2-12 carbon atoms, and R⁶ is an alkyl group having 1-6 carbonatoms; or a group having the formula:

wherein R⁷ is:

or —[C(CH₃)₂]_(n)—, wherein n is 1-10, preferably 1-8 carbon atoms andR⁸ is an organic moiety.

Examples of suitable hydrocarbyl and substituted hydrocarbyl groupsinclude straight chain or branched chain alkyl groups having 1-16 carbonatoms; straight chain or branched chain C₁-C₁₆ alkyl groups substitutedwith an acyloxy group, a haloalkyl group, an alkoxy group, a halogenatom, a cyano group, or a haloalkyl group; straight chain or branchedchain alkenyl groups having 2 to 16 carbon atoms; straight chain orbranched chain alkynyl groups having 2 to 12 carbon atoms; cycloalkylgroups; arylalkyl groups; alkylaryl groups; and aryl groups.

The organic moiety R⁸ may be substituted or unsubstituted and may bestraight chain, branched or cyclic, saturated, unsaturated or aromatic.Examples of such organic moieties include C₁-C₈ alkyl moieties, C₂-C₈alkenyl moieties, C₂-C₈ alkynyl moieties, C₃-C₁₂ cycloaliphaticmoieties, aryl moieties such as phenyl and substituted phenyl andaralkyl moieties such as benzyl, methylbenzyl and phenylethyl. Otherorganic moieties include substituted hydrocarbon moieties, such as halo(e.g., chloro-, fluoro-and bromo-substituted hydrocarbons) andoxy-(e.g., alkoxy substituted hydrocarbons) substituted hydrocarbonmoieties. Preferred organic radicals are alkyl, alkenyl and alkynylmoieties having from 1 to about 8 carbon atoms, and halo-substitutedderivatives thereof. Particularly preferred are alkyl moieties of 4 to 8carbon atoms.

In the cyanoacrylate monomer of formula (IV), R³ is preferably an alkylgroup having 1-10 carbon atoms or a group having the formula -AOR⁹,wherein A is a divalent straight or branched chain alkylene oroxyalkylene moiety having 2-8 carbon atoms, and R⁹ is a straight orbranched alkyl moiety having 1-8 carbon atoms. Examples of groupsrepresented by the formula -AOR⁸ include 1-methoxy-2-propyl, 2-butoxyethyl, isopropoxy ethyl, 2-methoxy ethyl, and 2-ethoxy ethyl. Thepreferred alpha-cyanoacrylate monomers used in this invention are2-octyl cyanoacrylate and butyl cyanoacrylate.

In preferred embodiments of the present invention, the cyanoacrylatemonomers can be prepared according to methods known in the art, forexample, U.S. Pat. Nos. 2,721,858 and 3,254,111, each of which is herebyincorporated in its entirety by reference. One such process includes,for example, reacting a cyanoacetate with formaldehyde in the presenceof a basic condensation catalyst at an elevated temperature to produce alow molecular weight polymer. A de-polymerization (or cracking) step isfollowed under high temperature and high vacuum in the presence ofacidic and anionic inhibitors, yielding a crude monomer that can bedistilled under high temperature and high vacuum in the presence ofradical and acidic inhibitors. In preferred embodiments, the distilled2-cyanoacrylate monomers are then formulated with free radical andacidic inhibitors to provide the necessary stability and other desiredphysical properties.

Without proper stabilization, the premature polymerization ofcyanoacrylate could be induced by 5,5-disubstitutedhydantoin. In orderto prevent the premature polymerization of cyanoacrylate monomers whenheating to dissolve the wound healing accelerator, and provide long termstability of cyanaocrylate formulations containing the accelerator,cyanoacrylate monomers are stabilized with the combination of freeradical and anionic stabilizers before the addition of the5,5-disubstitutedhydantoin (“pre-stabilized”). In embodiments of thepresent invention, the preferred primary free radical stabilizer isbutylated hydroxyl anisole (BHA). Other free radical stabilizers includewithout limitation, hydroquinone; catechol; hydroquinone monomethylether and hindered phenols such as butylated hydroxyanisol;4-ethoxyphenol; butylated hydroxytoluene (BHT, 2,6-di-tert-butylbutylphenol), 4-methoxyphenol (MP); 3-methoxyphenol;2-tertbutyl-4methoxyphenol; 2-tert-butyl-4-methoxyphenol;2,2-methylene-bis-(4-methyl-6-tert-butylphenol).

The amount of stabilizer to be used can be determined by one of ordinaryskills in the art using known techniques without undue experimentation.MP is used in an amount of about 1 ppm to about 4000 ppm, preferablyabout 100 to about 2000 ppm. Hydroquinone is used in an amount of about1 ppm to about 2500 ppm, preferably from about 50 ppm to about 1500 ppm.BHT is used in an amount of about 1 ppm to about 10000 ppm, preferablyfrom about 500 ppm to about 5000 ppm.

According to some embodiments of the present invention, the preferredanionic stabilizer is sulfur dioxide in an amount of about 2 ppm toabout 500 ppm, preferably about 10 ppm to about 200 ppm to pre-stabilizecyanoacrylate monomers before adding 5,5-disubstitutedhydantoin. Otheranionic stabilizers may be a very strong acid including withoutlimitation perchloric acid, hydrochloric acid, hydrobromic acid,toluenesulfonic acid, fluorosulfonic acid, phosphoric acid, ortho, meta,or para-phosphoric acid, trichloroacetic acid, and sulfuric acid. Thevery strong acid is used in an amount of about 1 ppm to about 250 ppm,preferably from about 5 ppm to about 50 ppm.

The compositions of the present invention generally contain the woundhealing accelerator and a stabilized polymerizable monomer. Thepolymerizable monomer, and the composition as a whole, are in liquidform and provide adhesive properties. Other components, known in theart, may also be included in the composition for their known effects andin known amounts.

According to some embodiments of the present invention, the compositionsmay optionally contain thickening agents. Suitable thickening agentsinclude polycyanoacrylate, partial polymer of cyanoacrylate,polycaprolactone, copolymers of alkylacrylate and vinyl acetate,polyalkyl methacrylates, polyalkyl acrylates, lactic-glycolic acidcopolymers, lactic acid-caprolactone copolymers, polyorthoesters,copolymers of alkyl methacrylates and butadiene, polyoxalates, andtriblock copolymers of polyoxypropylene flanked by two hydrophilicchains of polyoxyethylene. The preferred thickening agents are a partialpolymer of cyanoacrylate as disclosed in U.S. Patent ApplicationPublication No. 2009/0318583, and triblock copolymers of polyoxyalkyleneas disclosed in U.S. Patent Application Publication No. 2009/0317353.Preferably the thickening agent is miscible in cyanoacrylate monomercompositions at room temperature.

In certain embodiments of the present invention, the composition mayinclude a polymerization accelerator. Suitable polymerizationaccelerators are calixarenes and oxacalixarenes, silacrowns, crownethers, cyclodextrin and its derivatives, polyethers, aliphatic alcohol,various aliphatic carboxylic acid esters, benzoyl peroxide, aminecompounds such as triethyl amine, diethyl amine, butyl amine, isopropylamine, tributyl amine, N,N-dimethyl aniline, N,N-diethyl aniline,N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine,N,N-dimethyl-o-toluidine, dimethyl benzyl amine, pyridine, picoline,vinyl pyridine, ethanolamine, propanolamine and ethylene diamine,quaternary ammonium salts such as alkyl ammonium salts, amide-bondedammonium salts, ester-bonded ammonium salts such as alkylammonium salts,amide-bonded ammonium salts, ester-bonded ammonium salts, salts andalkylimidazolinium salts, cyclosulfur compounds and derivatives, andpolyalkylene oxides and derivatives.

Suitable crown ethers include, but are not limited to, 15-crown-5;18-crown-6; dibenzo-18-crown-6; tribenzo-18-crown-6;dicyclohexyl-18-crown-6; benzo-15-crown5; dibenzo-24-crown-8;dibenzo-30-crown-10; asym-dibenzo-22-crown-6; dimethylsila-11-crown-4;dimethylsila-14-crown-5; dimethylsila-17-crown-6; dibenzo-14-crown-4;dicyclohexyl24-crown-8; asym-dibenzo-22-crown-6; cyclohexyl-12-crown-4;1,2-decalyl-15-crown-5; 1,2naphtho-15-crown-5;3,4,5-naphthyl-16-crown-5; 1,2-methyl-benzo-18-crown-6;1,2methylbenzo-5,6-methylbenzo-18-crown-6; 1,2-t-butyl-18-crown-6,1,2-vinylbenzo-15-crown-5; 1,2-vinylbenzo-18-crown-6;1,2-t-butyl-cyclohexyl-18-crown-6; and1,2-benzo-1,4-benzo-5oxygen-20-crown-7. The preferred crown ether is18-crown-6.

Suitably, the crown ether is used in an amount of up to 2000 ppm,preferably 50 to 1000 ppm, and more preferably 100 to 500 ppm. Theamount to be used can be determined by one of ordinary skill in the artusing known techniques and without undue experimentation.

The compositions of this invention may further contain small amounts ofcolorants such as dyes, pigments, and pigment dyes. Suitable dyesinclude derivatives of anthracene and other complex structures. Thesedyes include without limitation, 1-hydroxy-4-[4methylphenylamino]-9,10anthracenedione (D&C violet No. 2);9-(o-carboxyphenyl)-6-hydroxy2,4,5,7-tetraiodo-3H-xanthen-3-one-,disodium salt, monohydrate (FD&C Red No. 3); disodium salt of6-hydroxy-5-[(4-sulfophenyl)axo]-2-naphthalene-sulfonic acid (FD&CYellow No. 6,);2(1,3dihydro-3-oxo-5-sulfo-2H-indole-2-ylidine)-2,3-dihydro-3-oxo-1H-ind-ole-5sulfonic acid disodium salt (FD&C Blue No. 2); and1,4-bis(4-methylanilino)anthracene-9,10-dione (D&C Green No. 6).

According to certain embodiments of the present invention, a plasticizermay be included in the inventive cyanoacrylate compositions. Theplasticizing agent preferably does not contain any moisture and shouldnot adversely affect the stability of the cyanoacrylate compositions.Examples of suitable plasticizers include, but are not limited to,tributyl citrate (TBC), acetyl tributyl citrate (ATBC), dimethylsebacate, diethylsebacate, triethyl phosphate,tri(2-ethyl-hexyl)phosphate, tri(p-cresyl)phosphate, diisodecyl adipate(DIDA), glyceryl triacetate, glyceryl tributyrate, dioctyl adipate(DICA), isopropyl myrisate, butyl sterate, lauric add, trioctyltrimelliate, dioctyl glutatrate (DICG) and mixtures thereof. Tributylcitrate, diisodecyl adipate and acetyl tributyl citrate are preferredplasticizers used in an amount of 0 to 30%, preferably 1% to 20%, andmore preferably 2% to 10%.

As discovered in the present invention, the 5,5-disubstitutedhydantoinincorporated into cyanoacrylate monomers at the elevated temperature,does not precipitate from the cyanoacrylate monomers after the solutionis cooled down to room temperature. This observation is important sincethe homogeneous solution of the healing accelerator in cyanoacrylatemonomers at room temperature can achieve even distribution on the tissueand more effective medicament delivery to the target site.

Table 1 below summarizes the results of incorporating phenytoin intodifferent cyanoacrylate monomer solutions at the elevated temperatures.As shown in Table 1, phenytoin is not soluble in 2-octyl cyanoacrylate(OCA) monomer at room temperature. At the elevated temperatures,phenytoin is soluble in both 2-octyl cyanoacrylate (OCA) and n-butylcyanoacrylate (BCA). It is also interesting to note that phenytoin ismore soluble in shorter alkyl chain cyanoacrylate (BCA) than in longeralkyl chain cyanoacrylate (OCA).

TABLE 1 Incorporation of phenytoin into different cyanoacrylates. Mixingtemperature Formulation OCA BCA Phenytoin (° C.) Miscibility 1a 100% 0%0.50% RT Not soluble 1b 100% 0% 0.12% 80 Soluble 1c  80% 20%  0.15% 70Soluble 1d 0 100%  0.30% 80 Soluble

The stability of the inventive liquid monomeric cyanoacrylate adhesivecompositions containing phenytoin was confirmed by accelerated agingtesting, which was performed in an oven at 80° C. for a period of about13 days. Based on calculations, 13 days of accelerated aging at 80° C.is equal to 2 years of shelf life, and 1 day of accelerated aging at 80°C. is equal to about 56 days. Throughout the entire aging testprocedure, all cyanoacrylate adhesive samples containing phenytoinremained in a fluid consistency. Viscosity was the measure of stability(industry standard) and the stability of the samples is set forth belowin Table 2. The viscosity of the cyanoacrylate compositions containingphenytoin were measured by a Brookfield DV-II+ Pro viscometer. Thespindle and sample chamber were cleaned with acetone after eachmeasurement. About 7 ml of the cyanoacrylate composition was put intothe sample chamber and the chamber was brought into position. The motorwas turned on after the sample was equilibrated in the sample chamber.The viscosity of the disclosed composition was measured in triplicate.Any residue was removed with acetone prior to the next samplemeasurement.

TABLE 2 Viscosities of cyanoacrylate adhesive compositions containingphenytoin before (Day 0) and after the accelerated aging test at 80° C.Average viscosity before and after accelerated aging (cps) Amount of DayDay Day Formulation Phenytoin Cyanoacrylate 0 3 6 Day 13 2a  0.1% OCA6.07 6.72 7.29 8.80 2b  0.1% OCA/BCA 4:1 5.32 4.32 6.07 8.66 2c 0.15%OCA 6.84 7.95 9.50 22 2d 0.15% OCA/BCA 4:1 5.38 5.58 6.40 7.47 2e 0.12%OCA 7.57 8.27 9.02 16.57 2f 0.12% OCA/BCA 4:1 5.32 5.74 6.39 6.82 2g0.12% BCA 4.77 5.27 5.58 10.13 2h 0.30% BCA 5.36 5.96 6.46 8.74

The viscosity of the cyanoacrylate adhesive composition containingphenytoin increased as the accelerated aging proceeded but the viscosityof the aged samples after day 13 was within an acceptable range whichdoes not affect the ability to dispense the adhesive from theapplicator. Actually, the increase of the viscosity of the mostpreferred cyanoacrylate adhesive compositions (a, b, d, f, and h) afterthe accelerated aging test is very little, indicating that the saidadhesive compositions were stable.

According to the present invention, any suitable applicator can be usedto store and apply the composition to the affected areas of skin.Suitable applicators and packaging systems may be any container whichmaintains the sterility and integrity of its contents. The preferredcontainer is also one which is compatible with the chosen method ofsterilization, including irradiation. The materials comprising thesuitable container are desirably irradiation stable under the maximumdosage of the sterilization. The suitable container also desirablyprovides a barrier to moisture so that it is compatible with thecyanoacrylate monomer compositions. Suitable applicators may be in anycontainer configuration such as, but not limited to a swab, vial, pouch,syringe, ampoule, or bottle, having an appropriate means, surface or tipto dispense the cyanoacrylate compositions from the container and applyonto the skin.

In embodiments, a preferred package or container for the compositions ofthe instant invention has multiple layers of different materials,including polymers and metal. Most preferred is a container wherein theinner layer is a nitrile polymer and the outer layer is polypropylene.The suitable package body may also be composed of an inner layer ofnitrile polymer and an outer layer of aluminum. The nitrile polymermaterial is preferably a copolymer composition, specifically,2-propenoic acid, methyl ester, polymer with 1,3-butadiene and2-propenenitrile, sold under the “BAREX” brand by BP Petrochemicals.BAREX® polymer provides high barrier properties which ensure thestability of the cyanoacrylate adhesive product stored therein. Theexceptional barrier properties offered by BAREX® polymers make them anideal inner layer material for use in construction of package bodies inaccordance with the present invention. BAREX® polymers offer a highbarrier to oxygen at all levels of relative humidity. This ensures thata consistently high barrier to oxygen is maintained, regardless of thehumidity of the surrounding environment. In addition, the water vaporbarrier properties of BAREX® polymers are comparable to other plasticpackaging materials and are ultimately enhanced by the outer layersecured thereto in accordance with the present invention.

The present invention, in embodiments, is applicable to single-usecontainers and may be applicable to applicators, where it is desired tomaintain a high degree of prolonged sterility and stability of thecomposition, by supplementing an optional sterilization treatment byaddition of the wound healing agent. Likewise, in embodiments, thepresent invention may also be suited for multiple-use containers orapplicators, where it is desired to maintain a high degree of prolongedsterility and stability of the composition against microbial actiondespite loss of initial sterility upon first use of the composition.

The antimicrobial properties of the wound healing agent of the presentinvention may operate to destroy microorganisms that may be present orgrow in the polymerizable monomer composition prior to use of thecomposition. The antimicrobial properties of the wound healing agent ofthe present invention operates to destroy microorganisms in and aroundthe application site subsequent to polymerization of the composition onthe desired application site such as a wound or incision. As set forthabove, many antimicrobial agents also function as polymerizationinhibitors, however, the wound healing agent of the instant inventiondoes not operate as such and does not affect polymerization of themonomer material.

Cyanoacrylate adhesive compositions for medical application arepreferably sterile. Sterilization of the monomer composition and/or itscontainer and/or packaging can be accomplished by any method, including,but not limited to chemical, physical and irradiation techniques.Examples of chemical methods include, but are not limited to, exposureto ethylene oxide and hydrogen peroxide. Examples of physical methodsinclude, but are not limited to, sterilization by heat (dry or moist) orretort canning. Examples of irradiation methods include, but are notlimited to, gamma irradiation, electron beam irradiation, and microwaveirradiation. Preferred methods of sterilization are chemical andirradiation methods, including but not limited to, electron beam(E-beam), gamma irradiation and X-Ray.

When sterilizing the compositions using E-beam irradiation, the doseapplied which is sufficient enough to sterilize the adhesivecompositions, typically, ranges from about 5 kGy to 50 kGy, and morepreferably from about 12 kGy to 25 kGy. E-beam irradiation is preferablyconducted at ambient atmosphere conditions and the exposure time to theirradiation is preferably within 60 seconds. Any standard power sourceis suitable, including a linear accelerator, which produces irradiationmeasured in kilo watts (KW). The larger the beam power, the more productvolume can be processed. The inventive cyanoacrylate adhesivecompositions are irradiated at a beam power ranging from about 2 KW toabout 30 KW, preferably about 5 KW to about 20 KW, and more preferablyabout 10 KW to about 20 KW. E-beam irradiation typically involves theuse of high-energy electrons. The beam energy ranges from 1 million to10 million electron volts (MeV), preferably 3 MeV to 10 MeV, and morepreferably 5 MeV to 10 MeV.

In order to reduce the bioburden, the inventive cyanoacrylate adhesivecompositions may be filtered through a 0.2 μm filter prior to E-beamsterilization. The inventive adhesive compositions may also besterilized with heat or ethylene oxide prior to the final E-beamirradiation.

In preferred embodiments of the present invention, the composition issterilized to provide a Sterility Assurance Level (SAL) of at least10⁻³. This means that the probability of a single unit being non-sterileafter sterilization is 1 in 1000. In more preferred embodiments, thesterility assurance level may be at least 10⁻⁴, 10⁻⁵, or 10⁻⁶. Aftersterilizing the inventive cyanoacrylate adhesive compositions, theirsterility levels were analyzed by Bacteriostasis and Fungistasis tests.After testing with challenging microorganisms such as Bacillus subtilis,Candida albicans, and Aspergillus niger, no growth of the microorganismswas observed, indicating the sterility of the inventive compositions.

Table 3 below shows the viscosity of some preferred cyanoacrylatecompositions, the same as in Table 2, before and after sterilizationwith E-beam irradiation. No significant change in the viscosity of theinventive compositions, was observed upon sterilization. The viscosityof these compositions increased only slightly after sterilization,indicating that the effect of sterilization on the compositions isinsignificant.

TABLE 3 Viscosity of the cyanoacrylate adhesive compositions containingphenytoin before and after sterilization. Viscosity (cps) Before AfterFormulation sterilization sterilization 2a 6.07 6.94 2b 5.32 6.04 2d5.38 6.12 2f 5.32 6.33

The changes in viscosity as measured before and after sterilization ofthe inventive compositions are desirably between about 0% and 100%,preferably between about 0% and about 80% and more preferably betweenabout 0% and about 40%. It is an advantage of the current invention thatthe integrity of the adhesive composition is maintained uponsterilization, as it has been reported in the literature that theviscosity of cyanoacrylate compositions often changes aftersterilization. Cyanoacrylate adhesives reported in the prior art havedemonstrated a 400% increase or more in viscosity induced bysterilization. And, often sterilization is used to intentionallyincrease the viscosity of cyanoacrylate adhesives. The compositions andmethod of making the compositions of the present invention minimize thevariation in viscosity of cyanoacrylate adhesives otherwise observed dueto sterilization.

Typically, for medical purposes, an adhesive should have a shelf-life ofat least one year; however, an increased shelf-life beyond this providesincreased economic advantages to both the manufacturer and the consumer.As used herein, shelf-life refers to the amount of time the containerand composition therein can be held at ambient conditions (approximatelyroom temperature) or less, without degradation of the composition and/orcontainer occurring to the extent that the composition and containercannot be used in the manner and for the purpose for which they wereintended. Thus, while some degradation to either or both of thecomposition and container can occur, it must not be to such an extentthat the composition and/or container are no longer useable. As usedherein, an “extended shelf-life” refers to a shelf-life of at least 12months, preferably at least 18 months, more preferably at least 24months, and even more preferably, at least 30 months.

To assess the stability of some of these same formulations as aboveafter sterilization, an accelerated aging test was performed. As usedherein “stability” refers to the resultant composition maintaining acommercially acceptable form for the prescribed amount of time. That is,the composition does not prematurely polymerize or otherwise change formor degrade to the point that the composition is not useful for itsintended purpose. Thus, while some polymerization or thickening of thecomposition may occur, such as can be measured by changes in viscosityof the composition, such change is not so extensive as to destroy orsignificantly impair the usefulness of the composition. The acceleratedaging test was performed in the oven at 80° C. for a period of 13 days.Based on calculations, 13 days accelerated aging at 80° C. is equal to 2years of shelf life, and 1 day of accelerated aging at 80° C. is equalto 56 days. Throughout the entire aging procedure, all cyanoacrylateadhesive samples retained fluid consistency and good color. Thestability of the aged samples was confirmed by viscosity tests. Theviscosity of the cyanoacrylate adhesive compositions slightly increasedas the accelerated aging proceeded indicating very little prematurepolymerization of the cyanoacrylate compositions occurred uponsterilization making them particularly suitable for medicalapplications. The average viscosity of the compositions at acceleratedaging day 0, day 3, day 6, day 10, and day 13 was 6.04, 7.66, 9.91,14.8, and 24.7 centipoise (cps), respectively. Additionally, it isexpected that this slight increase in viscosity at the end of theaccelerated aging will not affect the performance of the cyanoacrylateadhesives nor the ability of the compositions to dispense from theapplicator, indicating these sterilized cyanoacrylate compositionsprovide a shelf life of at least two years.

Accordingly, the instant inventive adhesive compositions containing a5,5-disubstitutedhydantoin, provide a stable shelf life for use in themedical field. The stability, and thus the shelf-life, of the inventivecyanoacrylate adhesive compositions were maintained during theaccelerated aging tests, the packaging and sterilizing procedures. Inpreferred embodiments, there is substantially no significantpolymerization of the monomeric liquid adhesive compositions that couldaffect the utility of the monomer.

Suitable ranges for the set time of the cyanoacrylate compositions ofthe instant invention is in the range from about 5 to about 120 seconds,more preferably from about 10 to about 80 seconds, and even morepreferably from about 15 to about 70 seconds.

The present invention further provides a kit for applying thecyanoacrylate adhesive composition containing 5,5-disubstitutedhydantoinas the wound healing accelerator, including an applicator containingtherein an effective amount of the cyanoacrylate composition. Anysuitable applicator can be used to apply the inventive composition tothe affected areas of skin. Suitable applicators may be any containersuch as, but not limited to, a swab, a vial, or any configuration havingan appropriate means, surface or tip to store and deliver thecyanoacrylate compositions from the container. The kit can furthercontain other appropriate practical elements to suit specific uses,including but not limited to surgical tools, other medicaments anddirections for application. When the present invention is used withother therapeutics or medicaments separate containers can be providedfor the cyanoacrylate composition and the therapeutic. Individualapplicators can be packaged separately to maintain sterile conditions.For example, each applicator can be packaged in plastic or any othersuitable enclosing material. Multiple applicators can then be packagedin a box for shipping.

The cyanoacrylate compositions of the present invention are particularlysuitable for use in medical application in terms of promoting woundhealing. In use, the cyanoacrylate adhesive composition is applied as aliquid to tissue to be sealed and then allowed to polymerize uponcontact with tissue to form an antimicrobial barrier film. The5,5-disubstitutedhydantoin incorporated within cyanoacrylatecompositions can accelerate the wound healing process during andfollowing its application to the skin.

Additional objects, advantages, and novel features of this inventionwill become apparent to those skilled in the art upon examination of thefollowing examples of the invention. The examples are included to moreclearly demonstrate the overall nature of the invention and, thus, areillustrative and not restrictive of the invention.

The shelf life stability of the inventive cyanoacrylate compositions wasevaluated by an accelerated aging test. 13 days of accelerated aging at80° C. is equal to 2 years at room temperature. The samples of thecyanoacrylate monomers containing phenytoin were placed in the oven at80° C. Samples were taken at day 3, day 6, day 10 and day 13 for themeasurement of viscosity and set time to evaluate the stability of thesaid adhesives.

The viscosity of the cyanoacrylate compositions containing phenytoinwere measured by a Brookfield DV-II+ Pro viscometer. The spindle andsample chamber were cleaned with acetone after each measurement. About 7ml of the cyanoacrylate composition was put into the sample chamber andthe chamber was brought into position. The motor was turned on after thesample was equilibrated in the sample chamber. The viscosity of thedisclosed composition was measured in triplicate. Any residue wasremoved with acetone prior to the next sample measurement.

Set time was measured using pig skin (4×4 square inch) prepared bywiping the surfaces of the skin with sterile gauze saturated withisopropanol. All oily substances were thereby removed from the pig skin.The surface was then wiped with sterile gauze to remove the isopropanol.A thin film of the cyanoacrylate composition was applied to the pig skinafter which elapsed time was recorded by a stop watch. Set time was thenrecorded by stopping the clock when the film was dry as determined atthe point where no liquid transfer occurred when the film was touchedwith a gloved finger.

EXAMPLES Example 1

To a three neck round bottom flask equipped with a thermometer and amagnetic stir bar, 118.7 g of 2-octyl cyanoacrylate monomer containing270 ppm of 18-crown-6 was stabilized with BHA and SO₂, which was mixedwith 0.12 g of phenytoin and stirred at 80° C. for about 2 hours. Afterit cooled down, no precipitate was observed and the resultingcyanoacrylate composition was a clear and homogeneous solution.

Example 2

A mixture of cyanoacrylate monomer including 80% 2-octyl cyanoacrylateand 20% n-butyl cyanoacrylate was stabilized with BHA and SO₂. 251.1 gof such mixture of cyanoacrylate was mixed with 0.25 g of phenytoin in athree neck round bottom flask. The resulting heterogeneous mixture washeated to 78° C. and stirred for about an hour until all phenytoin wasdissolved in the cyanoacrylate monomers. After cooling down to roomtemperature, the homogenous solution was stirred overnight at roomtemperature to check the miscibility of phenytoin with cyanoacrylatemonomers. 10 ppm of SO2 was added to the solution to stabilize thecyanoacrylate composition containing phenytoin.

Example 3

To a three neck round bottom flask equipped with a thermometer and amagnetic stir bar, 115.6 g of n-butyl cyanoacrylate monomer stabilizedwith BHA and SO₂ was mixed with 0.35 g of phenytoin and stirred at 80°C. until all visible solid particles of phenytoin were dissolved inn-butyl cyanoacrylate. After it cooled down, no precipitate was observedand the resulting cyanoacrylate composition was a clear and homogeneoussolution. The viscosity and set time of the resulting composition was5.36 cps and 14 seconds, respectively.

Example 4

115.8 g of 2-octyl cyanoacrylate monomer with BHA and SO₂ as the freeradical and anionic stabilizers, respectively, was mixed with 0.116 g ofphenytoin in a three neck round bottom flask. The resulting mixture wasstirred at 70° C. for about 1 hour until all of the phenytoin whitepowder was dissolved in the 2-octyl cyanoacrylate monomer to preparecyanoacrylate compositions containing phenytoin. After the solution wascooled to room temperature, no precipitate of phenytoin was observed.

While the invention has been described with reference to preferredembodiments, the invention is not limited to the specific examplesgiven, and other embodiments and modifications can be made by thoseskilled in the art without departing from the spirit and scope of theinvention.

We claim:
 1. A composition, comprising 2-octyl cyanoacrylate monomer, anamount of butylated hydroxyl anisole and sulfur dioxide effective tostabilize the 2-octyl cyanoacrylate monomer, and 0.05% to 0.3% by weightof the composition of phenytoin, wherein the composition is ahomogeneous mixture.
 2. The composition of claim 1, wherein saidcomposition is sterilized, and the viscosity of the sterilizedcomposition increases between about 0% and about 40% after sterilizationrelative to the viscosity of the composition prior to sterilization. 3.The composition of claim 1, further comprising up to 2000 ppm of apolymerization accelerator comprising 18-crown-6 crown ether.
 4. Thecomposition of claim 1, further comprising a plasticizing agent selectedfrom the group consisting of tributyl citrate, diisodecyl adipate andacetyl tributyl citrate.
 5. The composition of claim 1, furthercomprising a thickening agent selected from the group consisting of apartial polymer of a cyanoacrylate and a triblock copolymer ofpolyoxyalkylene.
 6. The composition of claim 2, wherein the compositionis sterilized by irradiation.
 7. The composition of claim 6, wherein thecomposition is sterilized by E-beam irradiation.
 8. The composition ofclaim 1, wherein the composition comprises 0.1% to 0.2% by weight of thecomposition of phenytoin.
 9. A kit, comprising an applicator and thecomposition of claim
 1. 10. A method of treating tissue, comprisingapplying the adhesive composition of claim 1 to a tissue surface, andallowing said composition to polymerize on said tissue surface.
 11. Acomposition, comprising n-butyl cyanoacrylate monomer, an amount ofbutylated hydroxyl anisole and sulfur dioxide effective to stabilize the2-octyl cyanoacrylate monomer, and 0.2% to 0.8% by weight of thecomposition of phenytoin, wherein the composition is a homogeneousmixture.
 12. The composition of claim 11, wherein said composition issterilized, and the viscosity of the sterilized composition increasesbetween about 0% and about 40% after sterilization relative to theviscosity of the composition prior to sterilization.
 13. The compositionof claim 11, further comprising up to 2000 ppm of a polymerizationaccelerator comprising 18-crown-6 crown ether.
 14. The composition ofclaim 11, further comprising a plasticizing agent selected from thegroup consisting of tributyl citrate, diisodecyl adipate and acetyltributyl citrate.
 15. The composition of claim 11, further comprising athickening agent selected from the group consisting of a partial polymerof a cyanoacrylate and a triblock copolymer of polyoxyalkylene.
 16. Thecomposition of claim 12, wherein the composition is sterilized byirradiation.
 17. The composition of claim 16, wherein the composition issterilized by E-beam irradiation.
 18. The composition of claim 11,wherein the composition comprises 0.3% to 0.5% by weight of thecomposition of phenytoin.
 19. A kit, comprising an applicator and thecomposition of claim
 11. 20. A method of treating tissue, comprisingapplying the adhesive composition of claim 11 to a tissue surface, andallowing said composition to polymerize on said tissue surface.